Oil & Fuel Can I Really Not Use CJ-4 Oil in my BX-25D?

coveredbridge · Feb 6, 2019

Performing 800 hr maintenance on my BX-25D. Finished changing all the oils (HST, Engine, Front Axle Case) and filters. Reviewing my manual and noticed a section that says "The CJ-4 engine oil is intended for DPF type engines, and cannot be used on this tractor." This seems to contradict the lubricant specs in the same manual that state for Engine oil: API Service Classification CF or higher.

I was always told that API class is backward compatible so if you use the latest classification you will be ok. At the last oil change I used Delo 10W-30, API Class CK-4. I had about 1 1/2 qt of that left which I used on this change along with Rotella 10W-30 API Class CJ-4. Both of these oils claim to meet or exceed the requirements of CF, CF-4, CG-4, CH-4 and CI-4, which Kubota seems to be saying I must use instead of CJ-4 (or I assume CK-4).

Also, Kubota's own oil is API Class CJ-4. So can I use the latest API class oil or do I have to check each time for specific backward compatibility with the classes listed in the manual?

Also, what about my old JD820? Is specifies API Class DM. Where am I supposed to find that? :confused2:

Blondie70 · Feb 6, 2019

I found that it's ok to use CJ-4 in my new L2501 as long as I don't run bio-diesel. Guess your's would be the same.

diesel85 · Feb 6, 2019

^ Exactly.

But I know this thread will turn into one of those "Bob is the oil guy" threads... lol

rScotty · Feb 9, 2019

coveredbridge said:
Performing 800 hr maintenance on my BX-25D. Finished changing all the oils (HST, Engine, Front Axle Case) and filters. Reviewing my manual and noticed a section that says "The CJ-4 engine oil is intended for DPF type engines, and cannot be used on this tractor." This seems to contradict the lubricant specs in the same manual that state for Engine oil: API Service Classification CF or higher.

I was always told that API class is backward compatible so if you use the latest classification you will be ok. At the last oil change I used Delo 10W-30, API Class CK-4. I had about 1 1/2 qt of that left which I used on this change along with Rotella 10W-30 API Class CJ-4. Both of these oils claim to meet or exceed the requirements of CF, CF-4, CG-4, CH-4 and CI-4, which Kubota seems to be saying I must use instead of CJ-4 (or I assume CK-4).

Also, Kubota's own oil is API Class CJ-4. So can I use the latest API class oil or do I have to check each time for specific backward compatibility with the classes listed in the manual?

Also, what about my old JD820? Is specifies API Class DM. Where am I supposed to find that? :confused2:

Yes, isn't that crazy? The manual for my 2008 M59 with an old style EGR for emission control says much the same thing. I can use CF or CI-4, but it warns against using CJ-4. Looking into the difference in the oil specs I believe Kubota's reasoning has to do with how soot is held in suspension in the oil. The different oils are made to be compatible with different soot-removal schemes. CI-4 for EGR engines, and CJ-4 for DPF engines. It is all about how the soot.

And since CK-4 is backward compatible to CJ-4, CK-4 oils would also be less suitable for an EGR equipped engine than CI-4.
But finding these old CI-4 oils for old EGR equipped tractors is getting to be difficult.

But there's a solution...not a good one, but acceptable. Since CI and CJ and CK is all about suspended soot and temperature resistance, the answer is easy. You can use the more recent formulations, but since they do not have to suspend soot in the engine oil so well, keep an eye on the motor oil and change it more often. That way you drain out the soot with the oil and by reducing the percentage of soot itself, you don't care how well the soot is being suspended.

Another option would be to disable the EGR valve assembly and fix (advance) the injector timing for better burning efficiency. They go together. Reburning spent exhaust fumes like an EGR does is certainly not an advantage for engine life. And a retarded injector timing creates soot and costs in fuel efficiency. The whole EGR seems like it was a mechanical mistake.

In my opinion EGR was an emission control method driven by legislation of a bygone era. It never was a good mechanical solution.....or good for the environment either. It was legislatively driven.

As I see it, EGR valving was part of a process designed to reduce the nitrous compounds in the exhaust as the law required at the time. But it did so at the expense of making more particles of soot because the soot loophole wasn't properly addressed in the original EC legislation.

As a result EGR engines have the potential to create a lot more smoke and particles. CI-4 oil was designed to help that by suspending the particles that got into the oil. And eventually about ( 2015) DPF or Particle Fluids arrived to take the soot out of the exhaust.

If your engine has an EGR (most did from 2006 to 2014/15 or so .... and most Tier IV Interm motors) then my best engineering guess is that you can use more modern oils but change them more often.

WHEW! I got way too WORDY on this....but I think the info is good.
rScotty

Fallon · Feb 9, 2019

DPF is Diesel Particle (maybe particulate) Filter (filters out soot).

DEF is Diesel Exhaust Fluid (urea, to help with the NOx emissions).

I hate those acronyms as well, way to easy to confuse them.

MHarryE · Feb 10, 2019

FA-4 oils are on-highway 2017 and newer and are not backward compatible. CK-4 oils should be backward compatible but Ford sent out a bulletin not to use them. The oils creating the problem were missing a wear additive. Top quality name oils should be okay but the CK-4 is a minimum. Large manufacturers set their own requirement. I do not know if Kubota has their own engine oil spec like they have UDT, Super UDT2, and Heavy Duty UDT for their hydraulic oils.